| The rotation angle between the proximal and distal axes of long bones is known as torsion, and it is thought to be indicative of the forces applied to the bone during growth. The humerus, for example, develops an internal twist or antetorsion, as daily activities are anterior to the body. However, the strong posterior stress induced by an overhead throwing motion may counteract this internal twist in young athletes and cause prominent bilateral dimorphism.;To measure torsion in these young athletes, a new technique using ultrasound has been developed and implemented in clinical practice. However, before widespread use in diverse populations, the technique must be validated against the existing benchmark based on computed tomography (CT) images.;The purpose of this thesis is to evaluate the validity, reliability, and precision of the novel ultrasound technique compared to CT in the assessment of humeral torsion, evaluating. This thesis first developed a standard CT measurement protocol that implements a quantitative method for selecting optimal CT images for analysis. The standard protocol showed significant improvement in precision when compared to a qualitative control method. The standard CT protocol and the ultrasound technique demonstrated above average intra and interobserver reliability and precision. When applied to shoulders without evidence of bone or joint pathology, was able to predict humeral torsion angles compared to the "gold standard" CT method within 5°, which suggests that the ultrasound method is a good predictor of humeral morphology. |
